1. Field of the Invention
The present invention relates to an apparatus for effectively managing purge water when obtaining liquid samples from a well or the like. More particularly, the present invention relates to an apparatus for storing purge water when obtaining liquid samples from a well, and then returning the purge water into the well. The United States Government has rights in this invention pursuant to Contract No. DE-AC09-89SR18035 between the U.S. Department of Energy and Westinghouse Savannah River Company.
2. Discussion of Background
Recent increases in public concerns for the environment have resulted in various government-imposed environmental laws, namely the Resource Conservation and Recovery Act (RCRA), and implementing regulations. Among such regulations are requirements relating to groundwater testing and monitoring. In response to these requirements, water quality analytical capabilities have been improved and water sampling equipment has been developed.
To obtain a groundwater sample from a monitoring well, it is necessary to purge the well by withdrawing three to four "well volumes" of water, and to stabilize certain indicator parameters. The water drawn from the well during the sampling process is called purge water, and is categorized as "investigation derived waste" (IDW) that must be managed as hazardous waste, in accordance with RCRA, when it contains constituents that are hazardous and/or radiological and exceed certain threshold limits. As a result of these regulations, the production of purge water requires its containerization and disposal as waste. The purge water, once in containers, must be transported to a disposal facility or treatment facility and handled respectively. Therefore, the amount of purge water created or produced is proportional to the expense required for its containerization, transportation, disposal, and/or treatment.
There are various devices that are used to reduce the amount of purge water created. U.S. Pat. No. 5,238,060 issued Aug. 24, 1993 to Niehaus, et al. discloses the use of an expandable bladder that seals the well into an upper and lower region. It is necessary, therefore, to purge only the lower region, before an effective sample may be taken. U.S. Pat. No. 5,147,561 issued Sep. 15, 1992, to Burge, et al.; U.S. Pat. No. 5,137,086 issued Aug. 11, 1992, to Stokely, et al.; and U.S. Pat. No. 4,717,473 issued Jan. 5, 1988, to Burge, et al., also disclose methods of dividing the well into a number of regions, thus reducing the amount of purge water produced or permitting multiple level sampling. However, these devices merely reduce the amount of purge water produced. Consequently, there is a need for an apparatus that can substantially eliminate the production of purge water, thereby avoiding the expense of its containerization, transportation, disposal, and/or treatment.